Most cultivated sunflower is grown as a source of vegetable oil. Thus, one of the principal goals of sunflower breeding programs is the development of F1 hybrid cultivars with high oil yield. Sunflower oil yield per unit area is determined by the product of seed yield per unit area and oil percentage in the seed. Therefore, consideration of both components is important when breeding for high oil yield hybrids.
Increased seed oil percentage is an important objective when breeding for high oil yield in sunflower. Although some researchers have investigated the genetics and heritability of sunflower oil percentage, most analyses were conducted on the oil percentage in the whole seed through conventional breeding and biometric procedures. This invention identifies restriction fragment length polymorphisms (RFLPs) linked to quantitative trait loci (QTL) affecting seed oil percentage, kernel oil percentage and kernel percentage. The advent of restriction fragment length polymorphisms (RFLPs) as genetic markers has enabled the development of linkage maps.
The number of factors controlling seed oil percentage or its components has not been discovered nor has their use in production of a genetically desirable inbred been suggested. However, some research has been done to study gene action involved in the expression of the traits. Additive, dominant, and epistatic effects were determined for seed oil percentage using two F.sub.2 populations and their reciprocal backcrosses. Estimates of General (GCA) and Specific Combining Ability (SCA) indicated additive effects were more important for seed oil percentage. Significant additive effects were also reported for seed oil, kernel oil, and kernel percentages, although significant dominant effects for seed oil percentage and kernel percentage were detected in irrigated conditions. Additive gene action has also been reported for hull percentage. Dominant and complementary effects for seed oil percentage and dominant effects for kernel oil percentage have been suggested. In general, these results indicate that additive effects predominantly influence oil percentage in the whole seed and its components; however, some non-additive effects also seem to affect these traits.
The difficulty in understanding the genetic basis of some traits may be due to the lack of knowledge about gene number, location, gene action and effects. This situation has focused the attention on the use of molecular markers to detect linkage with quantitative trait loci (QTL).
Cultivated sunflower is a diploid species (2n=2x=34) and is second only to soybean in its importance as an annual oilseed crop. However the genetics of only a small number of traits have been studied in detail as a consequence of this sunflower does not possess a classical genetic map. The only linkage reported to date is that between the nuclear genetic male sterility (GMS) gene and the T gene coding for anthocyanin pigmentation in the plant (Leclerq P (1966) Ann Amerlior Plantes 16:135-144). In addition the use of molecular markers in sunflower has only focused on the identification of interspecific crosses (Krauter R, et al (1991) Theor Appl Genet 82:521-525) and the taxonomy of the genus Helianthus (Choumane W, et al. (1988) Theor Appl Genet 76:481-489). A recent fingerprinting study of elite inbred lines has shown that there are high levels of restriction fragment length polymorphism in cultivated sunflower. Since sunflower is a diploid with developed inbred lines and segregating populations there remains a need to RFLP map the sunflower.